Which of the caller's workspaces an issue key opens in, for an old link

Totals for the issues the caller can see, grouped, honouring every filter listIssues honours because it shares the same query builder. A count walking a different predicate than the list beside it would put two numbers on screen that disagree, with neither looking wrong alone. Exists because a paged list cannot answer "how many". Group headers, board columns and the progress bars on the cycles and projects pages each need a real total per group, and one grouped query serves a whole screen where per-group requests would take one per column. Each group carries `total` and `done` - both, because a progress bar needs two numbers and fetching them separately would double the requests per bar. `done` counts issues whose state is of the `completed` type. `key` is always a string, including for priority, which groups on an integer column. A null key is a real group: unassigned, no project, or no cycle. Groups holding no issues are ABSENT rather than zero - the caller knows its own states, projects and cycles and can render those as zero, which the server cannot do for assignees.